Monthly Archives:: July 2012

Scientists have discovered that variations in the long-term reversal rate of the Earth's magnetic field may be caused by changes in heat flow from the Earth's core into the base of the overlying mantle.

According to a new Berkeley Earth study released July 29, the average temperature of Earth's land has risen by 1.5 °C over the past 250 years. The good match between the new temperature record and historical carbon dioxide records suggests that the most straightforward explanation for this warming is human greenhouse gas emissions.

On a time scale of tens to hundreds of millions of years, the geomagnetic field may be influenced by currents in the mantle. The frequent polarity reversals of Earth's magnetic field can also be connected with processes in the mantle. New results show how the rapid processes in the outer core, which flows at rates of up to about one millimeter per second, are coupled with the processes in the mantle, which occur more in the velocity range of centimeters per year.

Debate over the origin of large-scale polygons (hundreds of meters to kilometers in diameter) on Mars remains active even after several decades of detailed observations. Similarity in geometric patterns on Mars and Earth has long captured the imagination. Geologists have examined these large-scale polygons and compared them to similar features on Earth's seafloor, which they believe may have formed via similar processes.

A newfound gene may help bacteria survive in extreme environments. In the days following the 2010 Deepwater Horizon oil spill, methane-eating bacteria bloomed in the Gulf of Mexico, feasting on the methane that gushed, along with oil, from the damaged well. The sudden influx of microbes was a scientific curiosity: Prior to the oil spill, scientists had observed relatively few signs of methane-eating microbes in the area.

The greatest climate change the world has seen in the last 100,000 years was the transition from the ice age to the warm interglacial period. New research indicates that, contrary to previous opinion, the rise in temperature and the rise in the atmospheric carbon dioxide follow each other closely in terms of time.

A whole-genome analysis suggests that polar bear numbers waxed and waned with climate change, and that the animals may have interbred with brown bears since becoming a distinct species millions of years ago.

Scientists widely believe that volcanic particle size is determined by the initial fragmentation process, when bubbly magma deep in the volcano changes into gas-particle flows. But new research indicates a more dynamic process where the amount and size of volcanic ash actually depend on what happens afterward, as the particles race toward the surface.